Apparatus

ABSTRACT

An annular seal member comprising a seal body comprising a locating portion locatable against a wall element of an offshore structure, an inner surface, an outer surface and a lip portion that defines an open mouth of the seal member for receiving an elongate element therethrough; wherein the seal body is locatable against the wall element such that when a static pressure acting on the outer surface of the seal body exceeds a static pressure acting on the inner surface of the seal body a net positive pressure is exerted on the outer surface which at least partly deforms inwardly to provide a portion of the seal body for sealing against an outer surface of the elongate element. An offshore structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/337,785, filed Mar. 28, 2019, which is a U.S. National PhaseApplication of PCT/GB2017/052901, filed Sep. 28, 2017, which claimspriority to GB Application No. 1619657.8, filed Nov. 21, 2016, and to GBApplication No. 1616488.1, filed Sep. 28, 2016, each of which isincorporated herein in their entirety by reference.

BACKGROUND OF THE INVENTION

This invention relates to an annular seal and a support structure.

Offshore structures, such as wind turbines, have to deal with corrosionas most are constructed from standard offshore steel grades which arecorroded by sea water.

The surfaces of the structures can be coated with various types ofpaint, including those used by the shipping industry. However, paintgets damaged and so requires regular maintenance.

Offshore wind turbines face the added challenge of having to retrievepower generated by the turbine via a power cable. Typically, the cableextends downwardly to a monopile which supports the wind turbine andexits through a circular port provided in the monopile below sea level.In order to prevent sea water from entering the monopile and corrodingthe inside, seals are provided around the cable.

However, it has been shown that many existing seals tend to work looseor fail so that fresh oxygenated sea water enters the monopile andaccelerates corrosion. It has been further shown that once a seal hasbeen breached, the level of sea water within the monopile fluctuates,thereby exposing the inside of the monopile to high levels of oxygen andseawater thereby exacerbating the corrosion.

It is an aim of the present invention to at least partly mitigate theabove-mentioned problems.

According to a first aspect of the present invention there is providedan annular seal member comprising: a seal body comprising a locatingportion locatable against a wall element of an offshore structure, aninner surface an outer surface and a lip portion that defines an openmouth of the seal member for receiving an elongate element therethrough;wherein the seal body is locatable against the wall element such thatwhen a static pressure acting on the outer surface of the seal bodyexceeds a static pressure acting on the inner surface of the seal body anet positive pressure is exerted on the outer surface which at leastpartly deforms inwardly to provide a portion of the seal body forsealing against an outer surface of the elongate element.

The elongate element may comprise an umbilical or power cable or thelike.

The elongate element may be flexible.

The seal body may comprise a resilient material which deforms under thenet positive pressure.

The locating portion may comprise a flange portion.

The flange portion may comprise at least one recess region that extendscircumferentially around the flange. The recess region may comprise ahydrophilic material. The hydrophilic material may comprise rubber whichmay comprise polychloroprene, modified with a hydrophilic substance,which may comprise bentonite.

A hydrophilic material in the context of the present invention is amaterial which expands on absorption of water when not constrained. Itmay be termed an expandable hydrophilic material. An expandablehydrophilic material may be a hydrophilic material which exhibits anincrease in volume which is greater than 100% of the original (i.e. dry)volume, for example, greater than 200% of the original volume or greaterthan 500% of the original volume or greater than 1000% of the originalvolume. The hydrophilic material may expand by at least 500% or at least800% or at least 1000% of its original volume when saturated with water.The hydrophilic material may expand by not more than 1500%, for examplenot more than 1300% of its original volume when saturated with water.

A hydrophilic material comprising polychloroprene modified withbentonite is particularly effective as a hydrophilic material in salinewater, in particular water having a salinity concentration of at least2%, for example seawater having a salinity concentration of at least3.5%. Such a hydrophilic material is therefore particularly suitable forsealing submerged structures in a marine environment, such as a monopileand cable arrangement for an offshore wind turbine.

The flange portion may comprise at least one magnetic element forsecuring the flange portion to the wall element.

The seal body may comprise an intermediate portion extending in thedirection from the locating portion to the lip portion, at least part ofthe outer surface and at least part of the inner surface being providedon the intermediate portion wherein the intermediate portion convergestowards the lip portion.

The intermediate portion may be substantially frusto-conical.

The intermediate portion may define a chamber for receiving the elongateelement which is larger than the space occupied by the elongate elementwithin the chamber.

The lip portion may comprise at least one lip recess region that extendscircumferentially around an inner surface of the lip portion. The liprecess region may comprise a hydrophilic material. The hydrophilicmaterial may comprise rubber, which may comprise polychloroprene,modified with a hydrophilic substance, which comprises bentonite.

The seal body may comprise a resilient material. At least one split maybe provided along the length of the seal body such that the seal body isopenable along the split for insertion of an elongate element.

The seal body may comprise a first fastening portion on a first portionof the seal body adjacent the split and a second fastening portion on asecond portion of the seal body adjacent an opposite side of the split,wherein the fastening portions are arranged to be secured together. Thefirst and second fastening portions may have a hydrophilic material,such as the hydrophilic material described previously, disposed betweenthem to aid sealing between the fastening portions.

The seal body may comprise a flexible tubular element which extendsalong a region of the seal body between the lip portion and a portion ofthe seal body which is locatable against the wall element.

The flexible tubular element may be at least 1 m or at least 5 m or atleast 10 m or at least 20 m or at least 30 m in length.

The seal body may define a chamber through which when received, theelongate element extends, the chamber is configured for receiving anannular hydrophilic sealing element. The seal body may be configured toconstrain expansion of the hydrophilic sealing element within thechamber in at least one direction. The chamber may be cylindrical andthe seal body configured to constrain the hydrophilic sealing element ina radial direction. The seal body may be configured to allow expansionof the sealing element within the chamber in the axial direction. Theseal body may be configured to allow expansion of the sealing element byat least 5% of the original (i.e. dry) volume for example at least 10%of the original volume. The seal body may be configured to limitexpansion of the sealing element to not more than 50% increase inoriginal volume, for example not more than 20% increase in originalvolume.

At least a portion of the chamber may converge towards one end of thechamber. The chamber may converge at both ends of the chamber.

The seal body may be configured to constrain expansion of thehydrophilic sealing element within the chamber in a direction which isperpendicular to the direction in which the cable extends through thechamber when received in the chamber.

According to sixth aspect of the invention there is provided a sealingelement comprising a hydrophilic material, wherein at least a portion ofthe sealing element is helical. The sealing element may have free endssuch that the sealing element can be fitted to an elongate element byinserting the elongate element between a free end and an adjacent coilformed by the helical arrangement and then moving the elongate elementbetween the coils until the elongate element exits from between theother free end so that that the sealing element is wound around theelongate element.

The hydrophilic material may comprise rubber modified with a hydrophilicsubstance. The rubber may comprise polychloroprene. The hydrophilicsubstance may comprise bentonite.

The sealing element may comprise at least two coils or at least threecoils or at least four coils.

According to a second aspect of the invention there is provided anoffshore structure, comprising: a wall element which defines a chamber;at least one aperture through the wall element at a lower portion of thewall element; at least one flexible elongate element each extendingthrough a respective aperture in the wall element; and at least one sealbody each located at a respective interface region between the wallelement and a respective elongate element; wherein each seal body isarranged so that a respective water level within the chamber relative toa surrounding water level is maintained at a desired level to provide asealing pressure on the seal body to seal a respective interface regionto prevent ingress of sea water into the sealed space.

The wall element may be substantially cylindrical.

Each seal body may be disposed within the chamber.

Each seal body may be arranged such that a higher water level within thechamber than the surrounding water level provides a sealing pressure onthe seal body.

Each seal body may be arranged such that a water level within thechamber which is lower than the surrounding water level causes water toflow into the chamber through the seal body.

According to a third aspect of the invention, there is provided asealing arrangement comprising a tubular member and an annular sealingmember at one end, the annular sealing member having a seal bodycomprising a locating portion locatable against a wall element of anoffshore structure, an inner surface and an outer surface, wherein thelocating portion comprises a sealing portion which abuts the wallelement when the locating portion is located against the wall elementand the seal body is locatable such that a static pressure acting on theouter surface of the seal body exceeds a static pressure acting on theinner surface of the seal body a net positive pressure is exerted on theouter surface which urges the sealing portion into sealing engagementwith the wall element.

The sealing portion may be a flange portion. The flange portion may havea generally annular configuration. The tubular member may be a flat hoseconstruction. “Flat hose” is a term used in the art to describe a pipewhich can be rolled in a flat configuration. An example is an Oroflex™layflat hose marketed as OROFLEX 80.

According to a fourth aspect of the invention, there is provided a cableprotection system comprising a tubular member, such as a J-tube or anI-tube, and a sealing arrangement in accordance with the third aspect ofthe invention.

According to a fifth aspect of the invention, there is provided a cableprotection system comprising a tubular member, such as a J-tube or anI-tube, and a sealing arrangement in accordance with the first aspect ofthe invention.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described hereinafter,by way of example only, with reference to the accompanying drawings inwhich:

FIG. 1 is a schematic illustration of a support assembly for an offshorestructure located on a sea bed;

FIG. 2 is a schematic representation of part of the support assemblyshown in FIG. 1 comprising an annular seal;

FIG. 3 is a perspective view of the annular seal depicted in FIG. 2 inisolation;

FIG. 4 is a schematic representation depicting assembly of a supportstructure;

FIG. 5 is a perspective view of an alternative embodiment of an annularseal;

FIG. 6 is a diagram illustrating a J-tube arrangement;

FIG. 7 is a diagram illustrating a monopile arrangement;

FIG. 8A is a diagram illustrating a monopile arrangement;

FIG. 8B is a diagram illustrating apportion of the monopile arrangementshown in FIG. 8A;

FIG. 9 is a perspective view of a monopile arrangement corresponding tothe arrangement shown in FIG. 8A;

FIG. 10 is a partial sectional view of the monopile arrangement shown inshown in FIG. 9 ;

FIG. 11 is a partial sectional view of the monopile arrangement shown inFIGS. 9 and 10 ;

FIG. 12A shows part of the arrangement shown in FIGS. 9 to 11 ;

FIG. 12B shows fasteners;

FIG. 13 is a schematic representation of an arrangement comprising aJ-tube;

FIG. 14 shows a portion of the arrangement shown in FIG. 13 ;

FIG. 15 shows an arrangement comprising a J-tube connector in a firstconfiguration;

FIG. 16 shows the arrangement shown in FIG. 15 in a secondconfiguration;

FIG. 17 shows a seal body having a reinforcing element;

FIG. 18 shows a portion of a cable;

FIG. 19 shows an arrangement comprising a J-tube;

FIG. 20 shows a portion of the arrangement shown in FIG. 18 ;

FIG. 21 shows an embodiment of an annular seal;

FIG. 22 is an alternative view of the annular seal shown in FIG. 21 ;

FIG. 23 is a sectional view of the annular seal shown in FIG. 21 in use;

FIGS. 24A to 24C show portions of the arrangement shown in FIG. 23 indifferent states to aid explanation;

FIG. 25 is a perspective view of an embodiment of an annular seal;

FIG. 26 is a perspective view of the annual seal shown in FIG. 25 from adifferent perspective;

FIG. 27 shows the annular seal shown in FIG. 25 together with a portionof a cable arrangement;

FIG. 28A is a sectional view of the arrangement shown in FIG. 26 in usewhen in a first state;

FIG. 28B corresponds to the sectional view shown in FIG. 28A when in asecond state;

FIG. 29 is a perspective view of an embodiment of an annular seal;

FIG. 30 is a perspective view of the annular seal shown in FIG. 29 froma different perspective;

FIG. 31 shows the annular seal shown in FIG. 29 in use;

FIG. 32 is a perspective view of a sealing element;

FIG. 33 is a side view of the sealing element shown in FIG. 32 ; and

FIG. 34 is an end view of the sealing element shown in FIG. 32 .

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic representation of a support assembly 2 of anoffshore structure such as a wind turbine.

The support assembly 2 comprises a base in the form of a monopile 4which is fixed to the sea bed 6 by securing the lower end of themonopile 4 in a bore in the sea bed 6.

The monopile 4 is tubular and comprises a cylindrical outer wall 5having a wall thickness which is not less than 25 mm and not greaterthan 200 mm. The diameter of the monopile 4 is approximately 6000 mm atthe base. The monopile 4 is fabricated, at least in part, from a metalsuch as steel. The monopile 4 defines an internal chamber 7 whichextends upwardly within the monopile 4. The internal chamber 7 is sealedat the bottom, either by the sea bed in which the monopile 4 is locatedor by an additional liner at the lower end of the chamber 7 which may beused if the monopile 4 is installed on porous sediment. The internalchamber 7 forms a reservoir in which water can be stored.

The monopile 4 extends upwardly from the sea bed so that it spans fiveenvironmental zones: the buried zone 8, the scour zone 10, the submergedzone 12, the splash/tidal range zone 14 and the atmospheric zone 16.

The lowermost zone is the buried zone 8, in which the monopile 4 isburied in the sea bed. Immediately above is the scour zone 10 in whichthe monopile is subject to abrasive particles from the sea bed.Immediately above the scour zone 10 is the submerged zone 12 in whichthe monopile 4 always remains submerged. Above the submerged zone 12 isthe splash/tidal range zone in which the monopile is periodicallysubmerged and exposed to the atmosphere due to fluctuations in waterlevel caused by tides, variations in atmospheric pressure and waves. Thehighest zone is the atmospheric zone which is typically above thehighest level that the surrounding water that could be reasonablyexpected to reach over the lifetime of a wind turbine, such as themaximum wave height that could be expected over a 200 year period. Theportion of the monopile 4 in the atmospheric zone is therefore rarely,if ever, submerged.

An access port 18 is provided in the cylindrical outer wall 5 in theregion which occupies the submerged zone. In the embodiment shown, theaccess port 18 is circular and has a diameter of approximately 450 mm.The access port may be ovoid or any other suitable shape.

The support assembly 2 further comprises an elongate cable arrangement20, such as a cable protection system comprised of a single tube, whichextends downwardly within the internal chamber 7 from a hang-off clamp22 at the top of the monopile 4. The cable arrangement 20 extends fromthe internal chamber 7 through the access port 18 to where it isconnected to a power network. The cable arrangement 20 comprises mainpower cables for transmitting power generated by the wind turbinetogether with service cables. The power cables and service cables areprotected by a tubular sleeve which is commonly referred to as a cableprotection system. The diameter of the access port 18 is greater thanthe diameter of the cable arrangement 20 in order to enable easyinstallation and to accommodate flexing of the cable arrangement 20.

The support assembly 2 further comprises an annular seal 24, having aninner surface 24 a and an outer surface 24 b, which surrounds the accessport 22 and the cable arrangement 20.

FIG. 2 shows a schematic representation of a portion of the supportassembly 2 shown in FIG. 1 in the region of the annular seal 24. Theannular seal 24 comprises a seal body having a flange portion 26, aconical portion 28 and a tubular portion 30. The flange portion 26 formsthe base of the annular seal 24 which abuts the outer wall 5 of themonopile 4. The conical portion 28 has a larger diameter end joining theflange portion 26 and a smaller diameter end joining the tubular portion30. The conical portion 28 converges in the direction away from theflange portion 26 and defines a chamber 29 which converges from theflange portion 26 to the tubular portion 30. Alternatively, the conicalportion 28 could comprise a bellows arrangement in order to improvearticulation of the seal 24. The tubular portion 30 has an innerdiameter which corresponds to the outer diameter of the cablearrangement 20 so that the tubular portion 30 forms a sleeve over thecable arrangement 20 which is in contact with the outer surface of thecable arrangement 20. The diameter of the tubular portion 30 correspondsto the diameter of the narrow end of the conical portion 28. The other,wide, end of the conical portion 28 has a diameter which is greater thanthe diameter of the cable arrangement 20. The tubular portion 30 definesa lip which forms an open mouth of the annular seal 24. In someembodiments, the tubular portion 30 could be bonded or mechanicallyfixed to the cable arrangement.

The surface of the flange portion 26 which abuts the outer wall 5 hasradially inner and outer circumferentially extending grooves 32, 34.FIG. 3 shows the annular seal 24 in isolation. The circumferentialgrooves 32, 34 are held apart by circumferentially spaced webs 36.Circumferentially spaced apertures 38, 40 are provided in the walls ofthe grooves 32, 34 respectively. The apertures 38, 40 provide fluidcommunication between each of the circumferential grooves 32, 34 andbetween the inner groove and the inner chamber 29 defined by conicalportion 28.

Hydrophilic elements may be placed within the grooves 32, 34 to expandonce the annular seal 24 is submerged. The hydrophilic elements improvesealing against the outer wall 5.

The annular seal 24 is formed from a compliant material such as anelastomer or rubber which allows the flange portion 26 to conform to theshape of the inner surface of the outer wall 5. The material shouldpreferably be sufficiently flexible so that the annular seal 24 canaccommodate movement between the cable arrangement 20 and the outer wall5 of the monopile 4 and resilient so that it maintains sealingengagement with the tubular portion 30 and the cable arrangement 20. Theannular seal 24 is a moulded component with the circumferential grooves32, 34 and webs 36 formed integrally.

A mechanical fixing 42 in the form of a ring, shown in FIG. 2 , securesthe flange portion 26 to the outer wall 5 of the monopile 4. It will beappreciated that the annular seal 24 may be secured to the outer wall 5by other means such as an adhesive, a retention slot provided on theouter wall 5 for receiving the flange portion 26, a clamping arrangementor a magnetic fastener. The flange portion 26 may be reinforced, forexample by a steel/composite ring to prevent a pressure differenceacting across the flange portion 26 from distorting its shape.

The tubular portion 30 of the annular seal 24 may be provided withcircumferential ribs to stop the annular seal 24 from sliding along thecable arrangement 20.

The material of the annular seal 24 may be reinforced with fibres, suchas aramid fibres, on the top and bottom in order to react moment forcesas tensile forces.

The support assembly 2 is assembled by attaching the flange portion 26of the annular seal 24 to the inner surface of the outer wall 5 of themonopile 4. The base of the monopile 4 is then secured in position onthe sea bed (or any suitable underwater structure). One end of the cablearrangement 20 is drawn through the access port 18 and through theannular seal 24 surrounding the access port 18 into the internal chamber7 of the monopile 4. The cable arrangement 20 is then hoisted up throughthe internal chamber 7 and connected to the hang-off clamp 22 at the topof the monopile 4.

When installed, the internal chamber 7 is filled with water (depicted bydiagonal lines thin the chamber 7) to a level which is equal to orgreater than the height of the top of the splash zone. The internalchamber 7 may be filled by pumping water directly into the internalchamber 7. Alternatively, once the support assembly 2 is installed, thewater level on the outside of the monopile 4 (depicted by diagonal linesin the external region of the monopile) could be allowed to risenaturally for example, by a rising tide. The increased pressure on theoutside of the monopile 4 caused by the increase in the water level actson the inner surface of the conical portion 28 of the annular seal 24which is exposed to the surrounding water via the access port 18. Theincrease in pressure against the conical portion 28 forces the tubularportion 30 out of contact with the outer surface of the cablearrangement 20 allowing water to flow into the internal chamber 7. Oncethe water level within the chamber 7 reaches the same level as thesurrounding water, the tubular portion 30 returns to contact the outersurface of the cable arrangement 20 to seal the internal chamber 7.

As surrounding water level drops, for example as the tide recedes, orthe internal chamber 7 is filled above the level of the surroundingwater (as shown in FIG. 1 ), pressure exerted by the water within theinternal chamber 7 on the outer surface formed by the conical portion 28and the tubular portion 30 of the annular seal exerts a radially inwardforce on the conical portion 28 and the tubular portion 30 to hold thetubular portion 30 in sealing engagement with the cable arrangement 20.The annular seal 24 therefore acts as a one-way valve which preventswater from escaping the internal chamber 7.

Furthermore, each successive tidal cycle, atmospheric pressure variationor wave that temporarily increases the height of the surrounding waterabove the height of the water within the chamber causes water to flowthrough the annular seal 24 into the internal chamber 7 and soprogressively increases the height of the water level in the chamber 7.The arrangement is therefore self-regulating in maintaining the level ofwater within the chamber 7 at or above the level to which it isinitially filled. Consequently, even if an imperfect seal is formedbetween the annular seal 24 and the cable arrangement 20, the additionof a pump or the periodic increases in the surrounding water levelensures that the water level within the chamber 7 does not fluctuategreatly. Small gaps between the annular seal 24 and the cablearrangement 20 or the outer wall 5 of the monopile 4 could also beexpected to be filled by sediment once the support assembly 2 isinstalled, thereby reducing leakage from the internal chamber 7.

Once the level of the water within the internal chamber 7 is greaterthan the level of the surrounding water, the positive pressure acting onthe outer surface of the conical portion 28 and the flange portion 26holds the flange portion 26 in pressing engagement against the innersurface of the outer wall 5 of the monopile 4. The flange portion 26therefore conforms to the shape of inner surface of the outer wall 5 andsealing between the flange portion 26 and the outer wall 5 is unproved.Sealing of the flange portion 26 against the outer wall 5 is furtherimproved by the circumferential grooves 32, 34 which are in fluidcommunication with the chamber 29 defined by the conical portion 28 viathe apertures 38, 40 and are therefore at the same pressure as thechamber 29 and the surrounding sea water. A positive pressure differencebetween the top surface of the flange portion 26, which is exposed tothe water in the internal chamber 7, and the circumferential grooves 32,34 further improves sealing.

Maintaining a substantially constant level of water within the internalchamber 7 of the monopile 4 allows the oxygen to become depleted whichslows down the rate of corrosion within the monopile 4. The water withinthe internal chamber 7 also becomes stagnant over time and additives canbe added to inhibit corrosion.

It will be appreciated that in alternative embodiments the annular sealcould be located on the outer surface of the outer wall 5 of themonopile 4 such that the water level within the internal chamber 5 iskept lower than the level of the surrounding water. However, theembodiment described above in which the annular seal 24 is locatedwithin the internal chamber 7 is beneficial because the seal isprotected within the chamber 7 and so is less likely to be damaged.

The annular seal described above has the further benefit that it can beretrofitted to exiting wind turbines in which a cable arrangement exitsthough an access port in the support assembly. Firstly, the cablearrangement is disconnected within the wind turbine. Then, the annularseal is slid onto and along the cable arrangement so that the flangeportion is brought into contact with an outer wall. The flange portionis then held in position, for example by magnetic elements such asmagnetic elements bonded to the flange portion or magnetized ferriteelements within the flange material or bonding agents, and the cable canbe reconnected. The internal chamber is then filled, for example using apump, manual filling or naturally using tidal changes (as describedabove). Once the level of the water within the internal chamber exceedsthe surrounding water level, the seal becomes self-sealing, as describedwith respect to the first embodiment.

FIG. 5 shows an alternative embodiment of an annular seal 24 in whichthe surface of the flange portion 26 which makes contact with the outerwall 5 is curved to follow the profile of the outer wall 5. For example,the radius of curvature of the face of the flange portion 26 may besubstantially the same as the radius of curvature of the inner surfaceof the outer wall. The arrangement further improves sealing.

FIG. 6 shows a J-tube arrangement which is commonly used in the offshoreindustry. The J-tube has a bell-mouth which is sealable by an annularseal having at least some features common to the annular seals describedabove. The annular seal could also be used to deal entry to an I-tubewhich, unlike a J-tube, has a bell-mouth that faces directly downwardlywhen in situ.

FIG. 7 shows a typical arrangement of an offshore structure, such as amonopile for a wind turbine, in which the cable enters the base of themonopile at an angle of approximately 45 degrees with respect tovertical. Although the support assemblies shown in FIGS. 1 and 4 showthe cable entering a monopile at 90 degrees to the vertical, it will beappreciated that the schematics are intended to aid explanation and thatmonopiles have entry holes designed to industry standards which suggestthat cable entry should be at 45 degrees to the vertical, as shown inFIG. 7 . In such arrangements, the access port usually has an ovalshape.

Further arrangements will now be described with reference to FIGS. 8A to20 in connection with retro-fitting a seal member for offshorestructures, such as monopiles, in which existing seals have failed;providing a sealing solution for new offshore installations comprising ahollow structure such as a monopile; and providing a sealing solutionfor J-tubes or I-tubes which are known terms in the art of offshorestructures.

FIG. 8A shows a schematic representation of a support assembly 102 of anoffshore structure. The support assembly 102 is similar to the supportassembly 2 shown in FIG. 1 . FIG. 8A further illustrates: a monopile802; a rigid polymer tube or flexible flat hose 804; bellows 806;permanent magnets 808 bonded internally to bellows to initiate andtemporarily locate sealing interface; a cable protection system 810potentially with damaged seal allowing water exchange and aggressivecorrosion of monopile in inter-tidal zone; seawater level 812 insidestructure always higher than maximum sea level. However, should any partof the seal fail the system is self-energising and if the sea level wasever higher than the internal sea water level then the structure wouldautomatically fill up; maximum envisaged height 814 of sea level; and aflexible liner 816 which may be required for porous sediment.

FIG. 8B illustrates the following: bellows 820 covers existing cableprotection system including sealing interface (which could have failedor be leaking at slow rate); interface 822 between bellows/cone and tubemolded together during manufacture of bellows or clamped in positionagainst reinforcement rings which could be molded into bellows (as shownin FIG. 8B).

The support assembly 102 comprises a cable arrangement 120 and anannular seal 124 in the form of a bellow, which is similar to theannular seal 24 described above, connected to a sealing tube 125. Thesealing tube 125 extends upwardly from the annular seal 124 to atransition piece (not shown). The tube going to the transition piece maybe either a rigid polymer pipe (such as polyurethane, polyethylene ornitrile rubber) or a flat hose construction which is to ship andtransport and retrofit onto a cable protection system offshore.

The annular seal 124 and the sealing tube 125 may be moulded together,for example as an integrally formed component, or clamped together. Theannular seal 124 could, for example, comprise a reinforcement ringagainst which the sealing tube 125 is clamped.

The tube 125 can perform at temperatures up to 90° C. It is alsocoilable and can easily be transported up to the Wind Turbine GeneratorTransition Piece, unlike a typical 60 m solid polymer pipe used in theoffshore industry.

In order to fit, fitters have to disconnect the power cable from ajunction box, slide the bellow 124 down the cable, with the tube 125(e.g. flat hose) already bonded in position to the bellow 124 (tominimize leak paths). When the bellow 124 makes contact with the innerwall of the monopile the geometry of the system, gravity and additionalguide ropes will enable the system to be installed roughly in the rightposition covering the monopile entry aperture for the cable and cableprotection system. As described previously, magnetic elements such aspermanent magnets can be bonded or otherwise fixed to the bellow 124 toprovide an initial sealing force at the sealing interface with themonopile. The fitted arrangement is shown in FIG. 9 .

When the tube 125 from the bellow has been secured topside in thetransition piece the inside of the monopile can be filled with water, toraise the differential pressure on the seal. If the sediment is porousit may be necessary to put a simple liner at the bottom of thestructure. Again, once the water level inside exceeds the outside heightthere will be a differential pressure which will move the seal againstthe sediment and internal wall structure to create a water tight seal.The filled monopile is shown in FIGS. 10 and 11 .

The connecting surface of the bellow 124 is profiled to the internaldiameter of the monopile or structure (for example, the surface abuttingthe inner surface of the monopile will have a radius of curvature whichcorresponds to the radius of curvature of the inner surface of themonopile e.g. corresponding to a monopile diameter of 5 m). The angle ofentry is typically 45 degrees for monopiles with no scour protection and15 degrees for monopiles with scour protection (rock layers).

The bellows construction shown in FIG. 12A would be a polymer such asrubber or polyurethane overmoulding a strong aramid or dyneema typefibre matting. This is to provide structural rigidity to react thecorresponding forces due to the differential pressures on each side ofthe flexible bellows/cone.

The reinforced rings can either have a tube connected to them direct bybonding them in during the bellows manufacturing process or polymer bandtype seals, as shown in FIG. 12B (HCL fasteners—smart band) could beused to provide a water tight seal once tensioned. If the reinforcedring on the bellows fits into the polymer tube the differential pressurewill create a water tight seal, providing the surface is of a suitableconstruction (clean, smooth, circular and flexible).

FIG. 13 illustrates part of a J-tube arrangement 202 connected to acable arrangement 230 for protecting a cable connected to an offshorestructure (not shown). The circled portion is shown in FIG. 14 . TheJ-tube is fitted with a sealing tube though which a cable can be drawn.A chamber is formed between the sealing tube and the outer wall of theJ-tube. A retainer holds the sealing tube against an inwardly directedflange at the end of the J-tube to hold the end of the sealing tube insealing engagement against the flange.

FIG. 14 illustrates the following: cable or flexible product 1402; pullin head 1404; retainer 1406; high pressure side 1408 (can be initiatedbefore cable is pulled in with J-tube connector/centraliser); polymertube or flat hose 1410 (installed onshore (low cost) such that thesealing interface can be tested onshore (this provides a major advantageover offshore installed seals as they cannot easily be tested, due totidal variations)); low pressure within polymer tube or flat hose 1412(free sea water exchange during tidal variations); and a single sealpoint 1414 for entire J-tube or I-tube.

In each embodiment in FIGS. 8 to 14 , the bellows makes the seal to thestructure which could be the monopile internal diameter or aJ-Tube/I-Tube internal diameter or end surface. Additionally, thearrangement will seal a monopile and J-Tube if the cable has a ‘yarn’outer sleeving (typically referred to in the art of submarine cables as“serving”), which cannot be used as an interface for a water tight seal.

FIG. 15 illustrates part of a J-tube arrangement in which the innersurface of the conical seal makes contact with the outer diameter of thecable and the external right facing seal face makes contact with apainted steel flat surface, which is welded in place as part of theJ-Tube construction. FIG. 15 further illustrates: a cable pull in head1502; cable or flexible product 1504 (50 mm to 300 mm) (must have smoothouter serving for water tight seal); J-tube connector 1506; and lowpressure inside J-tube 1508.

FIG. 15 shows the arrangement before installation, FIG. 16 shows thesame arrangement after installation in which a sealing face of theannular seal seals against an outer surface of the cable. FIG. 16illustrates the following: a sealing face 1602 (cable to seal); sealretainer plate 1604 (to prevent seal moving during installation);sealing face 1606 (seal to structure); low pressure (seawater side;1608); high pressure structure side (side which requires corrosionprotection; 1610).

FIG. 17 shows an annular seal, which may be a polymer seal, having andinternal reinforcement (shown in broken lines).

The described arrangements provide a simple preformed seal which has twoleak paths—one between the seal outer diameter and a supportingstructure and the other between the seal internal diameter and a cable(which must have a smooth water-tight outer serving, for examplepolyethylene or polyurethane as shown in FIG. 18 ).

An alternative iteration is to put a solid polymer pipe all the way downthe tube, as shown in FIGS. 19 and 20 . This is similar to the monopilesolution described above. This provides a solution if the cable is of ayarn type construction and a water type seal not possible.

Where suitable, sealing arrangements for a J-tube maybe used inconjunction with I-tubes.

FIGS. 21 and 22 show an embodiment of an annular seal 324 comprising aseal body having a flange portion 326, a conical portion 328 (identifiedin FIG. 22 ) and a tubular portion 330 similar to that shown in FIGS. 2and 3 .

The flange portion 326 has a first lip 332 which extendscircumferentially about the periphery of the flange portion 326 and afirst annular rib 334 which extends circumferentially and is spacedradially inwardly from the first lip 332 thus defining a first annulargroove 336 on the underside of the flange portion 326 between the firstlip 332 and the first rib 334. A plurality of first channels 338 extendin a radial direction along the first rib 334. The first channels 338are spaced apart from each other in a circumferential direction. In theembodiment shown, there are twelve channels 338 spaced apart equallyaround the first rib 334. It will, however, be appreciated that fewer ormore channels 338 could be provided. It is anticipated that the greaterthe number of channels 338 or the greater the cross-sectional area ofeach channel 338, the better diffusion of liquid into the first groove336, but the less support the first rib 334 provides for preventing thechannels 338 from being compressed under an applied force against theupper surface of the flange portion 326. The two requirements musttherefore be considered when setting the number and the size of thechannels 338. For example, the first rib 334 could be provided with atleast one channel in some circumstances. However, it is anticipated thatat least two channels or at least three channels would provide anacceptable performance and that in most circumstances, at least fourchannels would be desirable.

The tubular portion 330 has a second lip 340 which extendscircumferentially about the open end of the tubular portion 330 (i.e.the end of the tubular portion 330 which is spaced away from the conicalportion 328) and a second annular rib 342 which extendscircumferentially and is spaced axially (with respect to thelongitudinal axis of the tubular portion 330) from the second lip 340thus defining a second annular groove 344 on the inner surface of thetubular portion 330. A plurality of second channels 346 extend in anaxial direction with respect to the longitudinal axis of the tubularportion 330. In the embodiment shown, there are twelve channels 346spaced apart equally about the second rib 342. It will, however, beappreciated that fewer or more channels 346 could be provided. It isanticipated that the greater the number of channels 346 or the greaterthe cross-sectional area of each channel 346, the better diffusion ofliquid into the second groove 344, but the less support the second rib342 provides for preventing the channels 346 from being compressed undera force applied to the outer surface of the tubular portion 330. The tworequirements must therefore be considered when setting the number andthe size of the channels 346. For example, the second rib 342 could beprovided with at least one channel in some circumstances. However, it isanticipated that at least two channels or at least three channels wouldprovide an acceptable performance and that in most circumstances, atleast four channels would be desirable.

FIG. 23 shows the annular seal 324 arranged in use to seal a wall 348 ofa structure, such as a support assembly for an offshore structure,against a flexible elongate element 350, such as an elongate cablearrangement, which extends through an access port 352 provided in thewall 348. The flexible elongate element 350 has a diameter which is lessthan the diameter of the access port 352 so that a gap is providedbetween the edges/sides of the port 352 and the flexible elongateelement 350.

A first sealing element 354 is disposed within the first annular groove336. The first sealing element 354 is annular and has a cross-sectionalprofile which corresponds to the cross-sectional profile of the firstgroove 336 so that the sealing element 354 initially occupies at least80% of the volume of the of the first groove 336 and in the embodimentshown substantially all of the second groove 336. The first sealingelement 354 comprises a hydrophilic material which expands whensaturated with water. The sealing element 354 has raised features in theform of annular ribs 356 to facilitate expansion of the sealing element354 and help improve sealing.

The hydrophilic material may comprise rubber, such as polychloroprene,modified with a hydrophilic agent, such as bentonite. For subseaapplications, the hydrophilic material must expand in order to provideeffective sealing when exposed to seawater, typically having a salinityconcentration of not less than 2%, for example not less than 3.5%.

An example of a suitable hydrophilic material is the material suppliedunder the name Hydrotite™ by a company called Tph Bausysteme GmbH—(seehttp://www.tph-bausysteme.com/en/systeme-zur-fugenabdichtung/water-swelling-sealing/)and in Japan by a company called C.I. Takiron—(seehttp://www.cik.co.jp/eng/products/construction/hydrotite/).

A technical datasheet for Hydrotite™ can be found at:http://www.tph-bausysteme.com/fileadmin/templates/images/datenblaetter-englisch/TDS%20HYDROTITE.pdf.

If unconstrained, a suitable hydrophilic material expands when saturatedwith water having a salinity concentration of at least 2.5%, such as atleast 3.5%, to between 1000% and 1300% of its original (i.e. dry)volume.

The contents of these references are incorporated herein by reference.

A second sealing element 358 is disposed within the second annulargroove 344. The second sealing element 358 is annular and has across-sectional profile which corresponds to the cross-sectional profileof the second groove 344 so that the sealing element initially occupiesat least 80% of the volume of the of the second groove 344 and in theembodiment shown occupies substantially all of the second groove 344.The second sealing element 358 comprises a hydrophilic material whichexpands when saturated with seawater. The second sealing element 358 hasraised features in the form of annular ribs 360 to facilitate expansionof the sealing element 358.

The annular seal 324, wall 348 and flexible elongate element 350 definea cavity 362 which is in fluid communication with each of the accessport 352, first channels 338 and second channels 346. In FIG. 23 , thearrangement is shown in a configuration in which the first and secondsealing elements 354, 358 have been exposed to water such that they areboth saturated and consequently expanded into the volume availablewithin each of the respective first and second annular grooves 336, 344and so seal against the wall 348 and the flexible elongate element 350.The installation process will be described with reference to FIG. 23 andalso FIGS. 24A to 24C, in particular.

The annular seal 324 is threaded onto the flexible elongate element 350and brought into abutting engagement with an internal surface of thewall 348, as shown in FIG. 23 . In this configuration, the first lip 332seals against the inner surface of the wall 348 and the second lip 340seals against the outer surface of the flexible elongate element 350. Asthe water level rises within the structure (i.e. on the left-hand sideof the wall 348, as shown in FIG. 23 ) above the level of the annularseal 324 (as described with respect to the earlier embodiments), theincreased pressure acts on the flange portion 326 to press the first lip332 against the inner surface of the wall 348 and against the tubularportion 330 to press the second lip 340 against the outer surface offlexible elongate element 350. The first and second lips 332, 340therefore create a preliminary seal to seal the flexible elongateelement 350 with respect to the wall 348 about the periphery of the port352. At the same time, or subsequently, the level of water rises abovethe port 352 on the outside of the structure (i.e. on the right-handside of the wall 348, as shown in FIG. 23 ). Seawater therefore flows inthrough the gap between the edge of the port 352 and the flexibleelongate element 350 into the cavity 362. The seawater flows from thecavity 362 along each of the plurality of first and second channels 338,346 into the respective first and second annular grooves 336, 344 andinto contact with the first and second sealing elements 354, 358.

Initially, each of the first sealing element 354 is in an unexpandedstate, as shown in FIG. 24A (which shows a partial view in the region ofthe flange portion 326 shown in FIG. 23 rotated clockwise through 90degrees). The annular ribs 356 of the sealing element 354 are spacedslightly from the outer surface of the wall 348. It will be appreciatedthat in other embodiments the sealing element 354 may be in contact withthe surface against which it is to seal when in an unexpanded state.

As water flows through the first channels 338 into the first annulargroove 336 and into contact with the first sealing element 354, thefirst sealing element 354 expands, if the sealing element wereunconstrained by the wall 348 it would begin to enlarge as shown in FIG.24B (FIG. 24B is provided to aid explanation and to demonstrate theexpansion characteristics of the first sealing element 354). Expansionof the first sealing element 354, however, is constrained by the wall348 and so the ribs 356 are compressed against the inner surface of thewall 348, in the embodiment show, the groove 336 is configured such thatexpansion of the first sealing element is constrained so that it doesnot expand by more than 20% in volume. In other embodiments, expansionmay be constrained to not more than 10%. The first sealing element 354therefore exerts a force against the wall 348 and the ribs 356 arecompressed and flatted out to fill the channel formed between them. Thefirst sealing element 354, once expanded, therefore creates a fluidtight seal between the flange portion 326 and the wall 348 of thestructure.

Expansion of the first sealing element 354 is dictated by the rate atwhich seawater permeates the material. In the application described, theseal material is a seawater expandable rubber on a polychloroprenebasis. Such a material is known to expand, when unconstrained, to avolume which is not less than 1000% of its dry volume, for example up to1300% of its dry volume and in some circumstances up to 1500% of its dryvolume. Typically, a seal will begin to expand immediately on exposureto seawater, but typically will take between 20 and 40 days to expand toits fully expanded state. Initial expansion of the sealing element 354can be delayed by covering exposed surfaces with one or more protectivelayers or chemical treatments that inhibit or prevent seawater fromreaching the hydrophilic material for a predetermined period of time.For example protective layers or chemical treatments may be appliedwhich delay initial expansion by at least one day or at least one weekand up to two weeks, for example.

In the embodiment show, once the first sealing element is fully expandedit acts like an O-ring which is watertight to at least 5 bar, and may beconfigured, for example by selection of an appropriate sealing materialor by configuring the geometry of the sealing element with respect tothe geometry of the first annular groove 336, to be watertight up to 400bar.

The seal may be configured to be watertight at a typical water depth,for example 20 m depth of water. The corresponding net pressure at whichthe seal may be watertight will be not less than 0.2 bar, for examplenot less than 0.5 bar, for example not less than 1 bar, for example notless than 2 bar.

The second sealing element 358 exhibit characteristics which are similarto the characteristics of the first sealing element 358, but isconfigured in accordance with the required size, degree of expansion andgeometry.

In some embodiments, sealing by the lips 332, 340 will be adequate.However, it is expected that the hydrophilic material will beparticularly advantageous when sealing against uneven surfaces, forexample the external surfaces of scoured or dirty cables that may bepresent as a consequence of biofouling, sediment/debris or corrosion. Inaddition, the hydrophilic material will expand/reform to accommodatemovement of the seal and changes in the surface against which it sealsfor example as a consequence of corrosion. In other applications, thelip can be expected to provide adequate sealing and the lip may beconfigured to be suitably flexible to provide a seal against a specificsurface finish.

FIGS. 25 and 26 show a base component 424 a of an annular seal 424 whichis similar to the annular seals described previously. The base component424 a comprises a first seal body having a flange portion 426 and aconical portion 428. The flange portion 426 may be provided with amagnetic element to aid installation and sealing and described withrespect to the previous embodiments.

FIG. 27 shows an arrangement comprising the base component 424 aassembled with a cap 424 b which is secured on an upper end of the basecomponent 424 a to form the annular seal 424. The cap 424 b has a firstaperture 430 through which a cable arrangement 432 extends. In theembodiment shown, the cable has a diameter which is between 90 mm and180 mm, for example 100 mm.

FIG. 28A shows a cross-sectional view of the arrangement shown in FIG.27 when secured to a wall 434 of a structure. The base component 424 ahas a first cavity 436 provided at the top of the base component and hasa second aperture 438 aligned with the first aperture 430 and throughwhich the cable arrangement 432 also extends.

The cap 424 b has a second cavity 440 which aligns with the first cavity436 to define a generally cylindrical chamber 436, 440. Respective endportions 441 a, 441 b of the internal side walls of the base component424 a and the cap 424 b which define the chamber converge along the axisof the chamber such that the chamber narrows towards each end. A sealingelement 442 comprising a hydrophilic material is disposed within thechamber. The sealing element is cylindrical and has a constant diameteralong its length. The sealing element 442 has a bore along its lengthalong which the cable arrangement 432 extends. The length of the sealingelement 442 is less than the length of the chamber.

The chamber defined by the base component 424 a and the cap 424 b is notwatertight and so when the inside of the structure is filled with water,as described in connection with the previous embodiments, the chamberfloods. The sealing element 442 expands axially along the chamber inopposite directions so the ends of the sealing element 442 expand intothe tapered ends of the chamber. The cylindrical side wall of thechamber in the middle portion of the chamber and the tapered side wallsat each end prevent the sealing element 442 from expanding radially andso the sealing element 442 exerts a sealing force against the cablearrangement 432. The tapered end regions effectively increase thecompressive force on the ends of the sealing element 442 in the radialdirection as the sealing element is forced into the tapered regions as aconsequence of the axial expansion. The sealing effectiveness istherefore increased.

FIG. 29 shows an annular seal 524 which is similar to the annular sealsdescribed previously. The annular seal 524 comprises a seal body havinga flange portion 526, central portion 528 and a fastening portion 530.The annular seal 524 has a lengthwise split 532 through one side thatextends along the length of the annular seal 524. In the embodimentshow, the split 532 is provided along the shortest portion of theannular seal 524 to aid installation. The split 532 allows the annularseal 524 to be opened along its side in order to pass the seal 524 overa cable arrangement rather than having to thread the cable arrangementthrough the seal 524. Fasting portions 534 a, 534 b extend along therespective edges formed by the split 532. Each fastening portion 534 a,534 b forms a flange-like protrusion which extends perpendicularly withrespect to the longitudinal axis of the annular seal 524. Respectivesets of holes 536 a, 536 b are provided in each fastening portion 534 a,534 b. The sets of holes 536 a, 536 b are arranged so that the holes ofeach set 536 a, 536 b are aligned with each other for receiving afastener such as a bolt or rivet. In the embodiment shown, each set ofholes 536 a, 536 b comprises five holes. The fastening portions 534 amay have a hydrophilic material, such as the hydrophilic materialdescribed previously, located between them to aid sealing.

The central portion 528 comprises an attachment 538 at a lower regionfor attachment of a clump weight in order to aid installation byovercoming any natural buoyancy of annular seal 524 (when installed on asubmerged structure) or drag/restrictions in the installation apparatuswhen the annular seal 524 needs to be lowered into position.

In the present embodiment, the annular seal 524 is formed from amaterial having a resilience which allows for the annular seal 524 to beseparated along the split 532 for insertion of a cable arrangement.

FIG. 31 shows the annular seal 524 shown in FIG. 29 being used to form aseal between a cable arrangement 540 comprising a cable 542 and a cableprotection system 544 and a wall 546 of a structure, such as a monopilefor a wind turbine.

The cable protection system 544 comprises a sheath 547, a mechanicalconnector 548 having retaining features 550 which secure the connectorto the wall 546 of the structure, and a bend stiffener 552 which extendsfrom the connector 548 along a portion of the cable 542 to resistexcessive bending of the cable 542 in the vicinity of the connector 548during installation and subsequent operation.

A flexible tube 554 is secured to the fastening portion 530 of theannular seal 524. The flexible tube 554 extends from the fasteningportion 530 along the cable 542 over the free end of the bend stiffener552. A sealing element 556 is secured to the end of the flexible tube554 not connected to the fastening portion 530. The sealing element 556may comprise a hydrophilic material housed with a chamber defined by ahousing similar to the arrangement shown in FIGS. 28A and 28B. Theflexible tube 554 may be a flat hose having a split which corresponds tothe split 532 and may be zipped/bolted around the cable arrangement 540together with the annular seal 524 after installation of the cablearrangement 540 without having to disconnect the cable arrangement 540.The length of the flexible tube 554 may be set in accordance withrequirements. For example, in the embodiment shown, the length of theflexible tube 554 is sufficient for the sealing element 556 to sealagainst the cable 542 rather than the bend stiffener 552. In otherembodiments, the length of the flexible tube 554 is sufficient for thesealing element 556 to seal against a relatively clean portion of thecable 542, for example a portion of the cable 542 which is close to ahang-off point within a monopile. In other embodiments, the length ofthe flexible tube 554 is sufficient so that it can be connected directlyto a hang-off point rather than sealing directly against the cable 542.The length of the flexible tube 554 may be at least 1 m or at least 5 mor at least 10 m or at least 20 m or at least 30 m. In use, the flexibletube 554 may be pressed against the cable 542 and/or bend stiffener 552when the pressure within the flexible tube 554 is less than the externalpressure acting on the flexible tube 554, which can also be expected toimprove sealing. A void 558 is defined by the annular seal 524 aroundthe connector 548 for retention of debris, for example damagedcomponents. The flange portion 526 may be provided with a magneticelement to aid installation and sealing and described with respect tothe previous embodiments.

FIGS. 32 to 34 shows a sealing element 602 which is suitable for use inthe arrangement shown in FIGS. 25 to 28B and FIGS. 29 to 31 , inparticular.

The sealing element 602 is formed from a hydrophilic material asdescribed with respect to the previous embodiments. The sealing elementis a single piece of material forming an integrated structure which maybe moulded and then cut into the desired shape. The sealing element 602is helical and has a first end 604 and a second end 606. The sealingelement 602 of the embodiment shown has six coils 608 a, 608 b, 608 c,608 d, 608 e, 608 f between the first and second ends 604, 606. It willbe appreciated that fewer or more coils could be provided. For example,the sealing element 602 may comprise at least two coils, for example atleast three coils or at least four coils.

The sealing element 602 is resilient and so can be installed on anin-situ cable by inserting a cable between an end 602, 604 and anadjacent coil and then ‘winding’ the sealing element 602 onto the cableuntil it releases at the other end 602, 604. When exposed to water, thecoils 608 a, 608 b, 608 c, 608 d, 608 e, 608 f expand both axially andradially in order to seal against the cable and each other. The tortuousleak path defined by the helical arrangement provides excellent sealingto prevent leakage through the sealing element 602.

In the drawings like reference numerals refer to like parts.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of them mean “including but notlimited to” and they are not intended to (and do not) exclude othermoieties, additives, components, integers or steps. Throughout thedescription and claims of this specification, the singular encompassesthe plural unless the context otherwise requires. In particular, wherethe indefinite article is used, the specification is to be understood ascontemplating plurality as well as singularity, unless the contextrequires otherwise.

Features, integers, characteristics or groups described in conjunctionwith a particular aspect, embodiment or example of the invention are tobe understood to be applicable to any other aspect, embodiment orexample described herein unless incompatible therewith. All of thefeatures disclosed in this specification (including any accompanyingclaims, abstract and drawings), and/or all of the steps of any method orprocess so disclosed, may be combined in any combination, exceptcombinations where at least some of the features and/or steps aremutually exclusive. The invention is not restricted to any details ofany foregoing embodiments. The invention extends to any novel one, ornovel combination, of the features disclosed in this specification(including any accompanying claims, abstract and drawings) or to anynovel one, or any novel combination, of the steps of any method orprocess so disclosed.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

What is claimed is:
 1. An annular seal member, comprising: a seal bodycomprising a locating portion locatable against a wall element of anoffshore structure, an inner surface, an outer surface and a lip portionthat defines an open mouth of the seal member for receiving an elongateelement therethrough, wherein the seal body is locatable against thewall element such that when a static pressure acting on the outersurface of the seal body exceeds a static pressure acting on the innersurface of the seal body a net positive pressure is exerted on the outersurface which at least partly deforms inwardly to provide a portion ofthe seal body for sealing against an outer surface of the elongateelement, wherein the locating portion comprises a flange portion thatcomprises at least one circumferentially extending groove that comprisesa circumferentially extending recess region, and wherein at least oneaperture is provided in a circumferentially extending wall of thegroove.
 2. The seal member of claim 1, wherein the elongate elementcomprises an umbilical or power cable or the like, the elongate elementbeing flexible.
 3. The seal member of claim 1, wherein the seal bodycomprises a resilient material which deforms under the net positivepressure.
 4. The seal member of claim 1, wherein the recess regioncomprises a hydrophilic material, the hydrophilic material comprisingrubber modified with a hydrophilic substance.
 5. The seal member ofclaim 1, wherein the flange portion comprises at least one magneticelement for securing the flange portion to the wall element.
 6. The sealmember of claim 1, wherein the seal body comprises an intermediateportion extending in the direction from the locating portion to the lipportion, at least part of the outer surface and at least part of theinner surface being provided on the intermediate portion, wherein theintermediate portion converges towards the lip portion, the intermediateportion being substantially frusto-conical.
 7. The seal member of claim6, wherein the intermediate portion defines a chamber for receiving theelongate element which is larger than the space occupied by the elongateelement within the chamber.
 8. The seal member of claim 1, wherein theseal body comprises a resilient material and at least one split isprovided along the length of the seal body such that the seal body isopenable along the split for insertion of an elongate element.
 9. Theseal member of claim 8, wherein the seal body comprises a firstfastening portion on a first portion of the seal body adjacent the splitand a second fastening portion on a second portion of the seal bodyadjacent an opposite side of the split, wherein the fastening portionsare arranged to be secured together.
 10. The seal member of claim 1,wherein the seal body comprises a flexible tubular element which extendsalong a region of the seal body between the lip portion and a portion ofthe seal body which is locatable against the wall element.
 11. The sealmember of claim 10, wherein the flexible tubular element is at least 1 mor at least 5 m or at least 10 m or at least 20 m or at least 30 m inlength.
 12. The seal member of claim 1, wherein the seal body defines achamber through which, when received, the elongate element extends, thechamber is configured for receiving an annular hydrophilic sealingelement, and the seal body is configured to constrain expansion of thehydrophilic sealing element within the chamber in at least onedirection.
 13. The seal member of claim 12, wherein at least a portionof the chamber converges towards one end of the chamber.
 14. The sealmember of claim 12, wherein the seal body is configured to constrainexpansion of the hydrophilic sealing element within the chamber in adirection which is perpendicular to the direction in which the cableextends through the chamber when received in the chamber.
 15. The sealmember of claim 1, wherein the groove comprises an annular groove or aplurality of circumferential grooves held apart by circumferentiallyspaced webs.
 16. An annular seal member, comprising: a seal bodycomprising a locating portion locatable against a wall element of anoffshore structure, an inner surface, an outer surface and a lip portionthat defines an open mouth of the seal member for receiving an elongateelement therethrough; wherein the seal body is locatable against thewall element such that when a static pressure acting on the outersurface of the seal body exceeds a static pressure acting on the innersurface of the seal body a net positive pressure is exerted on the outersurface which at least partly deforms inwardly to provide a portion ofthe seal body for sealing against an outer surface of the elongateelement, wherein the lip portion comprises at least one lip recessregion that extends circumferentially around an inner surface of the lipportion.
 17. The seal member of claim 16, wherein the lip recess regioncomprises a hydrophilic material, the hydrophilic material comprisingrubber modified with a hydrophilic substance.
 18. A sealing elementcomprising a hydrophilic material, wherein: at least a portion of thesealing element is helical; and the sealing element has free ends suchthat the sealing element can be fitted to an elongate element byinserting the elongate element between a free end and an adjacent coilformed by a helical arrangement and then moving the elongate elementbetween the coils until the elongate element exits from between theother free end and an adjacent coil so that the sealing element is woundaround the elongate element.
 19. The sealing element of claim 18,wherein the hydrophilic material comprises rubber modified with ahydrophilic substance.
 20. The sealing element of claim 18, wherein thesealing element comprises at least two coils or at least three coils orat least four coils.